itoa的实现

#include <stdio.h>char * itoa(int num, char *str, int len);int main(void){int num = 12345;char str[7];int len = 5;char *pstr = itoa(num, str, len); printf("The num string is:%s\n", pstr);printf("The num string is:%s\n", str);return 0;}char * itoa(int num, char *str, int len){if(len <= 0){printf("Len must bigger than 0\n");return NULL;}int i=0, j=0;char temp[len+1];while(num){// got reserved stringtemp[i] = num % 10 + '0';++i;num = num / 10;}temp[i] = 0; printf("The temp string is:%s\n", temp);// reserved string again will got the right turni = i - 1;while(i >= 0){str[j] = temp[i];++j;--i;}str[j] = 0;return str;}